“Wavy” energetic ion dispersion events and PC-5 type magnetic field pulsations in auroral zones Original Research Article

In some energetic ion dispersion events observed in Auroral zone (ILAT=67−74°) by the DOK-2 instruments (Interball-1,2) time variations of the ion peak energies had periodical sinusoidal patterns superposed on a normal smooth hyperbolic decrease which is a result of a gradient-curvature drift of ions after their pulse injection (Lutsenko at al., 2000, 2002). The periods were from 3 to 7 min. We compared these “wavy” events with variations in a local magnetic field. The magnetic field data showed the existence of PC-5 type oscillations in the same time and with the same periods. In a local magnetic field frame the oscillations were transversal and mainly in the west-east direction. The phase correlation was such that the ion peak energy increases when the change in By is eastward and vice versa. A simple explanation of the phenomenon is given in a frame of the gradient-curvature drift model. The measured energy variations are connected with a drift shell oscillations in the longitude direction. Amplitudes of these oscillations were estimated for two events.